21+3 is a blackjack side bet that combines your first two cards with the dealer’s upcard to form a three-card poker-style hand. It can pay for hands such as a flush, straight, three of a kind, straight flush, or suited three of a kind, depending on the paytable.
Plain Talk
21+3 is not blackjack strategy.
It is a side bet sitting next to blackjack.
Your main blackjack hand still plays by blackjack rules. The 21+3 bet is resolved separately using only three cards: your two starting cards and the dealer’s face-up card.
That is why it feels fun. It gives blackjack players a poker-style bonus sweat before the hand even plays out.
It is also why you must price it separately.
For the broader warning, read Why Are Side Bets So Bad? and Blackjack.
Why People Ask This
Players ask because 21+3 looks harmless.
The main blackjack bet might be $10, and the side bet might be only $5. That feels small. But if you make the side bet every hand, it becomes a separate stream of action with its own house edge.
The Wizard of Odds 21+3 page explains common paytables and house edges. The key lesson is that the exact paytable matters.
What Actually Happens
21+3 pays based on poker-style combinations.
| 21+3 result type | What it means | Why players like it |
|---|---|---|
| Flush | Three cards same suit | Easy to recognize |
| Straight | Three connected ranks | Feels close often |
| Three of a kind | Same rank | Strong bonus feel |
| Straight flush | Connected and same suit | Higher payout |
| Suited trips | Same rank and suit pattern in special decks/paytables | Big-pay excitement |
Different casinos may use different paytables. That changes the math.
Official blackjack rules define the main game, while side bets may be approved as additional wagers. For example, Massachusetts blackjack rules describe blackjack procedures, and jurisdictions may approve specific optional wagers separately.
Example
You bet $10 on blackjack and $5 on 21+3.
Your cards are 8♠ and 9♠. The dealer upcard is 10♠.
Your 21+3 hand is a suited straight: 8♠-9♠-10♠.
The side bet may win according to the table’s paytable. Your blackjack hand still plays normally. You might win the side bet and lose the blackjack hand, or lose the side bet and win the blackjack hand.
| Bet | Uses which cards? | Resolved how? |
|---|---|---|
| Main blackjack | Your hand vs dealer hand | Blackjack rules |
| 21+3 | Your first two cards + dealer upcard | Poker-style paytable |
| Insurance | Dealer ace situation | Separate blackjack side bet |
| Other side bets | Varies by game | Separate math |
From the Casino Side:
From the casino side, 21+3 is attractive because it adds excitement and extra action to an existing blackjack table.
The dealer does not need to teach a whole new game. The side bet uses cards already being dealt. Players get a bonus sweat. The casino gets another wager with its own edge.
Side bets also help make low-minimum tables more profitable because a player may bet $10 on blackjack and another $5 or $10 on side action.
For the operations view, see Back of House and How Casinos Price Games.
The Common Mistake
The common mistake is thinking 21+3 is part of correct blackjack play.
It is not.
Basic strategy does not tell you to make 21+3. Card totals do not improve because you made 21+3. The side bet does not protect a weak blackjack hand. It is a separate wager with separate odds.
The player mistake is treating optional excitement as required action.
Hard Truth
21+3 makes blackjack feel more exciting, but excitement is not the same thing as better blackjack.
Quick Checklist
- Read the 21+3 paytable before betting.
- Treat it as a separate side bet, not blackjack strategy.
- Do not bet it automatically every hand.
- Track total action: main bet plus side bet.
- Compare side-bet cost with the main game.
- Avoid chasing because you “almost” hit a straight or flush.
FAQ
Is 21+3 part of blackjack?
It is offered on blackjack tables, but it is a separate side bet.
Does 21+3 affect my blackjack hand?
No. Your main blackjack hand plays normally.
Is 21+3 a good bet?
It depends on the paytable, but many side bets have higher house edges than the main blackjack game.
Can I win 21+3 and lose blackjack?
Yes. The side bet and main bet resolve separately.
Why do players like 21+3?
Because it adds poker-style excitement and higher payouts to a familiar blackjack table.
Deeper Insight
21+3 is a classic side-bet design.
It uses existing game materials, creates an easy-to-understand bonus event, and gives players a chance at larger payouts without learning a new table game. That is good entertainment design. It is not automatically good value.
The paytable is the whole story. A small change in payouts can move the house edge significantly.
Formula / Calculation
| Metric | Formula | Plain-English meaning |
|---|---|---|
| Side Bet Cost | Side Bet Amount × Side Bet House Edge | Expected cost of the optional bet |
| Total Amount Wagered | Main Bet + Side Bet | True amount in action per hand |
| Expected Loss | Total Amount Wagered × House Edge | Long-term cost of all action |
| RTP | 1 - House Edge | Long-term return rate |
Formula Explanation in Plain English
If you bet $10 on blackjack and $5 on 21+3, you are not playing only a $10 hand. You are putting $15 into action, with two different prices.
The main blackjack game may have a low edge with good rules and correct strategy. The side bet may have a very different edge. Do not blend them emotionally.
Related Reading
Use Ask a Veteran before adding side bets to a main game. Continue with Blackjack Side Bet Odds, Why Are Side Bets So Bad?, and Three Card Poker Odds. For key terms, read side bet, house edge, and expected value. For the myth side, see Why Side Bets Feel Better Than They Are and Blackjack.